Rookie Daniel Theis has been a solid contributor for the Celtics. (AP)

Boston Celtics rookie center Daniel Theis has suffered a torn meniscus in his left knee and will undergo season-ending surgery, league sources told Yahoo Sports.

Theis underwent further testing Monday morning after suffering the injury in Sunday’s home loss to Indiana. The 6-foot-10 center emerged as a critical part of the Celtics’ rotation this season, averaging 5.3 points and 4.4 rebounds in 63 games. He has helped bolster Boston’s frontcourt unit as a floor-spacer and defensive presence, along with Aron Baynes and Greg Monroe behind starter Al Horford.